Acoustic diaphragm and similar appliance



Dec. 22, 1931. w. B. HOLLINGSHEAD A ACOUSTIC D-IAPHRAGM AND SIMILAR APPLANGE Filed March 13, 1929 i wum-ED srA gous vibratory Patented Dec; 22, 1931 WILLIAM B. ioLLINes,Hmm,` or rUGxAHoE, NEW Yom.: jacoUsTIc DIABHRAGM .ANDV SIMILAR APPLIANUE Application 11i-ea karen l1a, i929. serial No. 346,560.

lty inventionV relates to acoustic diaphragms and analogous devices, and especially to means for damping,modulating,` or 'otherwise controlling the vibrations of such 5 devices. a p s In the `term acoustic diaphragms I intendto include the vibratory diaphragms of phonograph recorders and reproducers, as Well as the cones, diaphragms, or analoelements of radio receivers 'and sound amplifiers,` 1' y The presentapplication is a division and continuation in part of my priory application Serial No. 320,7 86 filed August 30, 1919, 15 with 'added modifications and improvements.

By study and experiment I havev found that acoustic diaphragms and the like `when permitted to vibrate freely or without resti-aint except by their normal support, as y in a frame or casing, inl many cases fail to providea true or faithful reproduction of the original sound. 'y The principal object of the present invention therefore is to properly controlling, damping or modulatlngsuch diaphragms, etc., to reduce or eliminate falseor excessive vibrations, and secure faithful recording or reproduction "with preservation ofxovertones,` and improved t tone qualities. f

A, further object is to provide adjustable damping means in orderrto controll damping or modulating effectsV and also to provide for unavoidable variations in the characteristics of the individual diaphragms or similar devices. These devices, even if supposedly identical, differ from each other, and adjustment' of the modulating means is 40 therefore in many cases necessary in order to `secure the desired tonal results from the individual Avibrating elements. f

` The characteristics and advantages ofthe inventionk are further sufficiently explained in connection with the following vdetail deand provide means for scription'f of the accompanying drawings,t which shows representative embodiments. After considering these examples, skilledpersons will kunderstand that many variations may `be -made Without "departing from' the principles disclosed., and \I contemplate the employment of any structures that are propferly within the scope of the appended'claims.

`Inthedrawings: "f

Fig. 1 is a front elevation of a'diaphragm 255 its case or housing, the arrangement selected being one adapted for phonographic recording or reproduction. t

F'ig. 2is a sectionat 22, F ig.11.

ig. 3 is a front elevation of a modifiedo structure. F.F ig. 4 is a partial section, enlarged, at 1-4,

Fig. 5 is a'diagram, giving one illustration or theoretical operation of the invention de- B5 vlces. -Y f Figs. 1 and 2 show one preferred embodiment of theinvention, this being one of those disclosed in the above identified application. The diaphragm support or sound-box 1 as70 Well as the diaphragm 2, may vary greatly in form, structure and arrangement, the particular structureshown being only representative, in the broader aspect of the invention.

This particular device is intendedl for phono- T graphic recording or reproducing, and for that purpose the case is connected to a neck portion 7, by Which it is attached to any soundvibration transmitting arm l(not shown); or the case 1 may be attached toi'SO the tone arm of a phonograph reproducer,

in any known-or suitable way. The case may be open or may have a closed back, as -:at 3. The diaphragm may be ofthe free type, Y or may be supported in any suitable way, as 35 by rings or gaskets 4 of suitable material, in some cases rubber-or rubber vcom osition, with orV Without clearance. The gasets and diaphragm may besecured by an annular collar orouter ring 5, secured by screws 6,2130

las the dampers 9 and the screws may if desired be arranged to control the compression of the diaphragmsupporting rings or gaskets. A stylus bar is connected to the diaphragm at a suitable point and has means for supporting the stylus in any known or suitable Way. The stylus connection may be at the center of the diaphragm as at 7a in Figs. 1 and 2, or near one edge thereof, as at 7b in Fig. 3, since I have found that in some cases more faithful response of the diaphragm to the original impulse is provided by the latter location.

As one suitable modulating means, I show certain parts or sectors of the diaphragm as engaged by damping points or plugs 9 and 10 respectively, (Figs. 1 and 2). These spaced plugs are shown as carried by a slide 11, circumferentially adjustable Within a slot or annular guideway 12 provided in the outer ring member 5, above referred to. By means of this construction thedamper may be adjusted circumferentially about a periph- .eral portion of the diaphragm to bring the damping elements into engagement With any two sectors or portions desired; and the slide can be easily adjusted until the best effect is obtained. rI'his damping effect is indicated graphically in Fig. 5, Where alternate portions 12 and 13 are designated as the crests of Waves 14 and 15, from which it will appear Vthat the dampers 9 and 10 check the vibrations of these portions or sectors of the diaphragm, While leaving the outer portions free to vibrate. rIhe sinusoidal line 16 of Fig. 5 may otherwise be considered or eX- plained as in effect a string7 of a musical instrument, representing a circle in the diaphragm at the same radius from the centre and 10. Evidently the dampers then establish nodal points in the same Way that a node is produced in a string by fingering (as in a violin or similar instru* ment), thus practically tuning the ydiaphragm. Evidently by properly positioning and adjusting the dampers, one nodal point may be made to either favor or suppress eX- cessive high notes (high frequency vibrations) While the other may similarly be made properly to control the lOW notes (low frequency vibrations).

Figs. 8 and 4 show a modification in which one of the dampers is adjustable in relation to the diaphragm. Each of the dampers 9 and 10a is carried by a short arm 20, and these arms have flanged peripheral or base portions 21 engaging in a channel formed by a flat ring 22 and an outer ring 23, secured to the case 1 in any suitable Way, as by screws 6 of the previous example. Ring 23 is so formed and provided With a shoulder 24 as to slidably retain the damper-supporting arms and prevent their displacement from the guide channel. A similar arrangement may be provided in Figs. 1 and 2 to retain the slidable member 11 in its channel.

Either or both of the dampers (Figs. 3 and 4) may be moved in a circular direction to obtain the desired vibration controlling effect, one such adjusted position of one of the dampers being indicated in dotted lines at 28, Fig. 3; or if desired, one of the dampers may be fixed in position, as by a pin inserted at 25 through plate 23 and the base of the supporting arm 20.

Skilled persons Will understand how the structural and operative principles disclosed may be applied to other acoustic diaphragms or sound reproducers, such as radio loudspeakers, or the sound reproducers of public address amplifying systems, etc.

I claim:

1. In combination With 'an acoustic dia phragm or analogous device, a plurality of dampers in contact With the diaphragm, and means for supporting at least one of the dampers adjustably in relation to the diaphragm to produce a variable nodal point thereon.

2. In combination with an acoustic diaphragm or analogous device, a plurality of dampers in contact With the diaphragm, and means for supporting the dampers adjustably in relation to the diaphragm to produce variable nodal points thereon.

3. In combination with an acoustic diaphragm or analogous device, a plurality of dampers in contact with the diaphragm, and means for supporting the dampers adj us tably in relation to each other to produce a plurality of variable nodal points on the diaphragm.

4. In combination With an acoustic diaphragm or analogous device, a plurality of dampers in Contact with the diaphragm, and means for supporting the dampers adjustably in relation to each other and to the diaphragm to produce a plurality of regulable nodal points therein.

5. In a structure of the character described, a diaphragm or analogous vibratory acoustic device, a support therefor, and a damper carried by the support and adjustable in a generally circumferential direction in relation to the diaphragm to produce a variable nodal point thereon.

I6. In a structure of the character described, a diaphragm or analogous vibratory acoustic device, a support therefor, and a plurality of dampers mounted on the support and adj ust able in a generally circun ferential direction in relation to the diaphragm to produce a corresponding plurality of variable nodal points thereon.

7. In appliance of the class described, the combination of a diaphragm, a support therefor including 4an annular channel, a dampersupporting element mounted for adjustable movement in the channel, and a damper carried thereby and opposed to the diaphragm to produce a variable nodal point thereon.

8. In appliance of the class described, the

combination of 'a diaphragm, a support therefor including an annular channel, a plurality of damper-supporting elements mounted in the channel and at least one of them adjustable in a generally circumferential direction,

and dampers carried by said elements and opposed different WILLIAM B. HOLLI to the diaphragm to produce in eifect nodal points therein. In testimony whereof I affix my signature. N GSHEAD 

